1.1. Three protein peaks showing arylsulphatase activity have been isolated from the gut of the giant African snail Achatina achatina by ion-exchange chromatography on DEAE-cellulose. The two absorbed peaks A1 and A2 were eluted with a linear gradient formed from 300 cm3 of 50 mM Tris-HCl and 300 cm3 of 100 mM NaCl in 50 mM Tris-HCl pH 7.4. The unabsorbed fraction UA was later resolved into two fractions UA1 and UA2 on Sephadex G-200.2.2. Partial purification of the isolated fractions was achieved by ammonium sulphate precipitation and further chromatography on Sephadex G-200. Some kinetic properties of these enzymes have been measured and their apparent molecular weights determined by gel filtration.3.3. The partially purified preparations remained stable at room temperature and when incubated for 30 min at 55°C lost only about 15% activity.4.4. Neither the crude extract nor the isolated fractions, showed steroid sulphatase activity. The two absorbed fractions A1 and A2, but not the unabsorbed fraction, were active towards p-nitrophenyl sulphate (NPS). Chloride ions did not appear to affect the rate of hydrolysis of NPS. Phosphate ions nearly completely inhibited the hydrolysis of dipotassium 2-hydroxy-5-nitrophenyl sulphate (NCS) by all fractions.5.5. The existence of multiple forms of the enzyme is discussed in relation to its possible involvement in the various metabolic cycles of the organism.